Socio-emotional functioning plays a central role throughout the life-span and is a major factor in successful aging. Whereas losses are seen in many psychological and physical domains in old age, emotion appears to be an area of functioning that is relatively spared. In research supported by the parent grant for this competitive revision, we are studying socio-emotional functioning in different age groups using both cross-sectional and longitudinal designs. In the competitive revision, we propose to expand the scope of this work to consider sources of individual differences within age groups in four aspects of socio-emotional functioning: (a) emotional reactivity, (b) emotion regulation, (c) emotional understanding, and (d) emotion in long-term marriage. We will examine genetic contributions to these variations by studying relationships between objective, precisely measured behavioral and physiological markers of these aspects of socio-emotional functioning and well-characterized polymorphisms of genes involved in the regulation of neurotransmitters and neuropeptides that are highly relevant to socio-emotional functioning: (a) the catechol-o-methyl transferase (COMT) gene, b) the serotonin transporter (5-HTT) gene, (c) the vasopressin receptor 1a gene (AVPR1A), and (d) the oxytocin receptor gene (OXTR). The proposed research expands the scope of the parent grant by exploring individual differences within age groups in socio-emotional functioning and by studying these gene-behavior relationships. PUBLIC HEALTH RELEVANCE: This research project examines emotional functioning and social functioning, both of which are intimately connected to physical and mental health. Emotional and social functioning are studied in older adults, who are at heightened risk for physical health problems.